The Arduino Mega has three additional serial ports: Serial1 on pins 19 (RX) and 18 (TX), Serial2 on pins 17 (RX) and 16 (TX), Serial3 on pins 15 (RX) and 14 (TX). To use these pins to communicate with your personal computer, you will need an additional USB-to-serial adaptor, as they are not connected to the Mega’s USB-to-serial adaptor. To use them to communicate with an external TTL serial device, connect the TX pin to your device’s RX pin, the RX to your device’s TX pin, and the ground of your Mega to your device’s ground.

baud: The communication baud rate. 9600bps is default. Acceptable values that are compatible with the Arduino IDE are 2400, 4800, 9600, 19200, 38400, 57600, and 115200. You can use other baud rates, but you will be unable to communicate with the OpenLog through the Arduino IDE serial monitor.

escape: The ASCII value (in decimal format) of the escape character. 26 is CTRL+z and is default. 36 is $and is a commonly used escape character.

esc#: The number of escape characters required. By default, it is three, so you must hit the escape character three times to drop to command mode. Acceptable values are from 0 to 254. Setting this value to 0 will disable escape character checking completely.

verb: Verbose mode. Extended (verbose) error messages are turned on by default. Setting this to 1 turns on verbose error messages (such as unknown command: remove !). Setting this to 0 turns off verbose errors but will respond with a ! if there is an error. Turning off verbose mode is handy if you are trying to handle errors from an embedded system.

echo: Echo mode. While in command mode, characters are echoed by default. Setting this to 0 turns off character echo. Turning this off is handy if handling errors and you don’t want sent commands being echoed back to the OpenLog.

ignoreRX: Emergency Override. Normally, OpenLog will emergency reset when the RX pin is pulled low during power up. Setting this to 1 will disable the checking of the RX pin during power up. This can be helpful for systems that will hold the RX line low for various reasons. If Emergency Override is disabled, you will not be able to force the unit back to 9600bps, and the configuration file will be the only way to modify the baud rate.